Abstract
BackgroundHere, insight is provided into the present knowledge on free-living nematodes associated with chemosynthetic environments in the deep sea. It was investigated if the same trends of high standing stock, low diversity, and the dominance of a specialized fauna, as observed for macro-invertebrates, are also present in the nematodes in both vents and seeps.MethodologyThis review is based on existing literature, in combination with integrated analysis of datasets, obtained through the Census of Marine Life program on Biogeography of Deep-Water Chemosynthetic Ecosystems (ChEss).FindingsNematodes are often thriving in the sulphidic sediments of deep cold seeps, with standing stock values ocassionaly exceeding largely the numbers at background sites. Vents seem not characterized by elevated densities. Both chemosynthetic driven ecosystems are showing low nematode diversity, and high dominance of single species. Genera richness seems inversely correlated to vent and seep fluid emissions, associated with distinct habitat types. Deep-sea cold seeps and hydrothermal vents are, however, highly dissimilar in terms of community composition and dominant taxa. There is no unique affinity of particular nematode taxa with seeps or vents.ConclusionsIt seems that shallow water relatives, rather than typical deep-sea taxa, have successfully colonized the reduced sediments of seeps at large water depth. For vents, the taxonomic similarity with adjacent regular sediments is much higher, supporting rather the importance of local adaptation, than that of long distance distribution. Likely the ephemeral nature of vents, its long distance offshore and the absence of pelagic transport mechanisms, have prevented so far the establishment of a successful and typical vent nematode fauna. Some future perspectives in meiofauna research are provided in order to get a more integrated picture of vent and seep biological processes, including all components of the marine ecosystem.
Highlights
Light in the deep sea only penetrates in the upper layers of the water column, so that photosynthesis is limited to a few 100 meters water depth
It is expected that the nematode standing stock at deepsea seeps and vents is depending on the availability of food, suggesting that the in situ chemosynthetic production may lead to elevated nematode densities and/or biomass compared to the adjacent phytodetritus fed sediments
Conclusions hydrothermal vents and cold seeps have biochemical similarities, distinct differences are present in the standing stock, diversity and taxonomical composition of the meiofauna in both types of ecosystems
Summary
Light in the deep sea only penetrates in the upper layers of the water column, so that photosynthesis is limited to a few 100 meters water depth. The local diversity, in contrast, is in general high on the deep-sea floor, the true extent of regional or global biodiversity is still unknown [1,2,3] Remarkable exceptions on these general trends of high local diversity and low density and biomass are ecosystems, known as hydrothermal vents [4], and cold seeps [5]. These systems are largely driven by chemosynthetic derived energy, and not directly dependent on photosynthesis. It was investigated if the same trends of high standing stock, low diversity, and the dominance of a specialized fauna, as observed for macro-invertebrates, are present in the nematodes in both vents and seeps
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
